return Arrays.copyOf(empty, length);
  }

  /** Equivalent to Arrays.copyOfRange(source, from, to, arrayOfType.getClass()). */
  static <T extends @Nullable Object> T[] copy(Object[] source, int from, int to, T[] arrayOfType) {
    T[] result = newArray(arrayOfType, to - from);
    System.arraycopy(source, from, result, 0, to - from);
    return result;
  }

   */
  @SuppressWarnings({"nullness", "unchecked"})
  static <T extends @Nullable Object> T[] copy(Object[] source, int from, int to, T[] arrayOfType) {
    return Arrays.copyOfRange(source, from, to, (Class<? extends T[]>) arrayOfType.getClass());
  }

  /**
   * Configures the given map maker to use weak keys, if possible; does nothing otherwise (i.e., in

   */
  @SuppressWarnings({"nullness", "unchecked"})
  static <T extends @Nullable Object> T[] copy(Object[] source, int from, int to, T[] arrayOfType) {
    return Arrays.copyOfRange(source, from, to, (Class<? extends T[]>) arrayOfType.getClass());
  }

  /**
   * Configures the given map maker to use weak keys, if possible; does nothing otherwise (i.e., in